EXTENSION OF THE TELEPHONE SYSTEM TO SHIES 171 



scribed, since they will be the subject of another paper to be given 

 before The Institute of Radio Engineers shortly by the engineers 

 immediately responsible for this development. Field strength meas- 

 urements will be discussed, therefore, only in so far as the results 

 obtained apply to the ship-to-shore type of system. 



The first measurements which were made are given in Fig. 18. They 

 show the variation in the strength of field received from the S. S. 

 Gloucester during the same trip as the circuit measurements of Fig. 14 

 were taken. The fact that the transmission is considerably better 

 to the northeast from Deal Beach than when the vessel is south is 

 rather strikingly in evidence. The dash-line curve is for the Austin- 



TRANSMISSION TEST 

 Deal Beach and S, S. Gloucester 

 Jul* 27. 1921 

 South Bouno on Course hf,320 Kilo-otoles 



Fig. 18 



Cohen formula and shows that the field strength versus distance 

 relation checks that formula for these relatively short wave lengths 

 when the path of transmission is practically entirely over sea. The 

 absorption coefficient is obviously greater when the path of trans- 

 mission has a relatively large component skirting along the coast 

 line. The curve shows also that the vessel was picked up and the 

 circuit "made" on this day at a field strength of about 400 micro- 

 volts per meter, then increased as the vessel came nearer and passed 

 the land station to a value of 2,200, and that the circuit was "broken " 

 on about 200 micro-volts. The results of another measurement made 

 at the off-shore course of the vessel are given in Fig. 19. A larger 



